1. Field of the Invention
The invention described in this specification relates to an A/D [analog-to-digital] converter, an operational amplifier, or a back electromotive force monitoring circuit.
2. Description of Related Art
Generally, an A/D converter is proposed, which performs a plurality of times of A/D conversion processing sequentially (cf., JP-A-2009-033861). However, the A/D converter leaves room for improvement as to an increase in processing speed.
Generally, an operational amplifier is proposed, which comprises an offset adjustment function (cf., JP-A-2008-004156). However, the operational amplifier leaves room for improvement as to reduction of a circuit scale and linearity of the offset adjustment.
Generally, a back electromotive force monitoring circuit is proposed, which monitors the back electromotive force generated by a motor (cf., JP-A-2002-063773). However the back electromotive force monitoring circuit leaves room for improvement as to accuracy in monitoring.